The present invention relates to a heat exchanger in which two different mediums come into contact with different duct walls to exchange heat, and the present invention also relates to a heat pump type air conditioning apparatus using the heat exchanger.
Conventionally, heat of a refrigerant which is heated utilizing a heat pump cycle is transmitted to liquid such as water through a heat exchanger, and the heated water is utilized as a heat source. For example, a heat pump cycle disclosed in Japanese Patent Application Laid-open No. 2002-98430 includes a first high-pressure side heat exchanger and a second high-pressure side heat exchanger, and the second high-pressure side heat exchanger exchanges heat between a high pressure refrigerant which flows out from the first high-pressure side heat exchanger and a second fluid with a lower temperature than that of a first fluid which exchanges heat in the first high-pressure side heat exchanger. A quantity of heat that can be taken out is equal to a sum of a quantity of heat that can be taken out by the first high-pressure side heat exchanger and a quantity of heat that can be taken out by the second high-pressure side heat exchanger. Therefore, the quantity of heat (enthalpy) that can be taken out by the heat pump is reduced, and coefficient of performance COP of the heat pump can be prevented from being deteriorated.